Chrysemys picta, the painted turtle, is a member of Emydidae within Cryptodira. There are four subspecies of C. picta: the eastern (C. p. picta), western (C. p. bellii), southern (C. p. dorsalis), and central (C. p. marginata) painted turtles, each of which is endemic to a particular region of the extensive range of this species, which covers most of the United States and includes parts of Mexico and Canada (Ernst and Barbour, 1989; Bonin et al., 2006). Emydidae contains the most species of any turtle group, and has an evolutionary record stretching back 80 million years (Ernst and Barbour, 1989; Bonin et al., 2006). Emydidae is closely related to the Old World pond turtles and tortoises (Geoemydidae and Testudinidae, respectively), but the relationship of these three close relatives to other turtles is unclear (e.g., Gaffney and Meylan, 1988; Joyce, in press).

Chrysemys picta is a small turtle, reaching 25 cm in length (Ernst and Barbour, 1989; Bonin et al., 2006). The skull is of moderate size with respect to the body and is somewhat emarginated. The carapace is oval and flattened, and the plastron is well developed. Chrysemys picta is olive to black dorsally with yellow or red borders on seams and red markings on the marginal scutes, and a medial red or yellow stripe is variably present. The plastron is yellow and may exhibit a dark blotch. The neck, legs, and tail are striped with red and yellow, while the head exhibits complex yellow markings that include large spots behind the eyes. Color patterns vary among subspecies (Ernst and Barbour, 1989; Bonin et al., 2006).

As described above, Chrysemys picta ranges across all of North America, from southern Canada to northern Mexico. It inhabits slow-moving, shallow water, and prefers locations with soft bottoms, plenty of vegetation, and suitable basking sites. It may enter brackish water along the Atlantic coast (Ernst and Barbour, 1989; Bonin et al., 2006). Young C. picta are carnivorous, but become omnivorous as adults. Painted turtles will feed opportunistically on almost any available food item. Females lay two to three clutches per year, each containing from two to 20 eggs, but do not reproduce every year (Ernst and Barbour, 1989; Bonin et al., 2006).

About the Species

This specimen was made available to the University of Texas High-Resolution X-Ray CT Facility for scanning by Dr. Heather Jamniczky of the University of Calgary. Funding was provided by Dr. Jamniczky and by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

About this Specimen

This specimen was scanned by Matthew Colbert on 5 August 2004 along the coronal axis for 660 slices. Each 1024 x 1024 pixel slice is 0.045 mm thick with an interslice spacing of 0.045 mm and a field of reconstruction of 21.3 mm.

About the Scan

Literature

Bickham, J.W. and J.L. Carr. 1983. Taxonomy and phylogeny of the higher categories of cryptodiran turtles based on a cladistic analysis of chromosomal data. Copeia 1983:918-932.